Started working up loads for a new rifle in 280 AI.
Tim Mc Whorter at flat creek precision did the build.
We used a fluted #4 brux 9 twist at 24" custom throated for 175 elite hunters. Unfortunately I have not been able to acquire any 175's so I started with 168 VLDH.
New Peterson brass was a crush fit so I pushed the shoulder back .002 on the new brass.
Intention was to establish a rough zero and get all 100 brass fired and some rounds on the barrel.
I started mid 50's with rl23 and cci250 primers.
Fired a few rounds and then worked my way up to 59 grains with the 168 at .030 jump. Never saw any pressure and the groups were decent but not great.
One thing I noticed is that RL23 fills the case quickly, 59 is bordering on compressed with a standard funnel.
After that I backed off to 57 grains and loaded for seating depth.
.010 jam
.010 jump
.050 jump
.090 jump
All were decent but .010 jump and .050 were both in the .4s so I went with .010 jump.
After that I did an OCW type test from 56.2 to 58 grains.
56.5 looked like the place to be, velocity was 2870 fps in the new brass.
I then tested primers with the same load and five shot groups.
CCI 250, CCI BR2 and 210M were tested which revealed very similar groups but the BR2 were slightly better.
Tried a few loads with RL26 and the 168's which was fairly uneventful except 58.5 gains which shot a tiny .058" group but I'm sure the speed was mid 2800's at best. I only have a couple pounds of 26 so not really going to pursue that.
After that I finished shooting the new brass with sierra 150 TGK's with RL23, RL26 and N565.
RL26 and N565 leave plenty of room in the brass compared to RL23.
I only shot increasing charge weights over the magnetospeed, so no groups. Rl26 and n565 were fairly slow with the 150's (high 2900's) but I just wanted to experiment so see where to start if I went that direction later on. Rl23 on the other hand was 3075 fps with 58.6 grains (compressed) and no pressure signs.
I now had 100 once fired brass and 100 rounds on the barrel so time to get a little more serious.
I cleaned the barrel and resized the brass to bump the shoulder .002 and size the necks to .311 which is .002 under the loaded dimension.
Using 1x Peterson brass, RL23, BR2 and 168 vld at .010 jump, I loaded 3 foulers at 58, 58.3 and 58.6 then groups of 57.7, 58, 58.3 and 58.6.
I shot the foulers over the chrono,
58, 2943
58.3, 2957
58.6, 2967
Shot all the groups while cooling 10 minutes between 3 shot groups.
All were on the same horizontal plane and under .7", they got smaller as they approached 58.6 which is .358"
I'll use this load for the next 50 rounds then check precision and velocity again if needed.
I know this jumped around a little but hopefully this will help someone with some of these components find a starting point.
Tim Mc Whorter at flat creek precision did the build.
We used a fluted #4 brux 9 twist at 24" custom throated for 175 elite hunters. Unfortunately I have not been able to acquire any 175's so I started with 168 VLDH.
New Peterson brass was a crush fit so I pushed the shoulder back .002 on the new brass.
Intention was to establish a rough zero and get all 100 brass fired and some rounds on the barrel.
I started mid 50's with rl23 and cci250 primers.
Fired a few rounds and then worked my way up to 59 grains with the 168 at .030 jump. Never saw any pressure and the groups were decent but not great.
One thing I noticed is that RL23 fills the case quickly, 59 is bordering on compressed with a standard funnel.
After that I backed off to 57 grains and loaded for seating depth.
.010 jam
.010 jump
.050 jump
.090 jump
All were decent but .010 jump and .050 were both in the .4s so I went with .010 jump.
After that I did an OCW type test from 56.2 to 58 grains.
56.5 looked like the place to be, velocity was 2870 fps in the new brass.
I then tested primers with the same load and five shot groups.
CCI 250, CCI BR2 and 210M were tested which revealed very similar groups but the BR2 were slightly better.
Tried a few loads with RL26 and the 168's which was fairly uneventful except 58.5 gains which shot a tiny .058" group but I'm sure the speed was mid 2800's at best. I only have a couple pounds of 26 so not really going to pursue that.
After that I finished shooting the new brass with sierra 150 TGK's with RL23, RL26 and N565.
RL26 and N565 leave plenty of room in the brass compared to RL23.
I only shot increasing charge weights over the magnetospeed, so no groups. Rl26 and n565 were fairly slow with the 150's (high 2900's) but I just wanted to experiment so see where to start if I went that direction later on. Rl23 on the other hand was 3075 fps with 58.6 grains (compressed) and no pressure signs.
I now had 100 once fired brass and 100 rounds on the barrel so time to get a little more serious.
I cleaned the barrel and resized the brass to bump the shoulder .002 and size the necks to .311 which is .002 under the loaded dimension.
Using 1x Peterson brass, RL23, BR2 and 168 vld at .010 jump, I loaded 3 foulers at 58, 58.3 and 58.6 then groups of 57.7, 58, 58.3 and 58.6.
I shot the foulers over the chrono,
58, 2943
58.3, 2957
58.6, 2967
Shot all the groups while cooling 10 minutes between 3 shot groups.
All were on the same horizontal plane and under .7", they got smaller as they approached 58.6 which is .358"
I'll use this load for the next 50 rounds then check precision and velocity again if needed.
I know this jumped around a little but hopefully this will help someone with some of these components find a starting point.
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